Semicolon-separated list list of macro names used by CMAKE_AUTOMOC to determine if a C++ file needs to be processed by moc.
This variable is used to initialize the AUTOMOC_MACRO_NAMES property on all the targets. See that target property for additional information.
The default value is Q_OBJECT;Q_GADGET;Q_NAMESPACE.
Let CMake know that source files that contain CUSTOM_MACRO must be moc processed as well:
set(CMAKE_AUTOMOC ON)
list(APPEND CMAKE_AUTOMOC_MACRO_NAMES "CUSTOM_MACRO")